Temperature probes are used in many applications for sensing the temperature of a solid, liquid or gas. For example, temperature probes are used in certain high energy laser systems to detect the temperature of basic hydrogen peroxide (BHP), iodine, chlorine and other chemicals used in the generation of the laser beam. Other applications include medical, pharmaceutical, food, chemical, aerospace and industrial applications. In certain applications, such as high energy laser systems, it is important to measure certain temperatures very accurately and very quickly.
Different classes of temperature sensors are known in the art to measure temperature. One class of temperature sensors employs resistive elements, well known to those skilled in the art. As the temperature of the element increases or decreases, the resistance of the element also increases or decreases providing an indication of the temperature change. A constant precision current signal is applied to the resistance element resulting in a voltage drop across the element proportional to its resistance and the temperature it is subjected to. The voltage is then measured to give a reading of the resistance, and thus the temperature corresponding with that particular resistance.
Known temperature probes that employ resistive elements typically have a response time (time constant) of several seconds. Particularly, when the temperature of the environment that the sensor is sensing changes, the sensor does not give the exact temperature reading for the change until more than several seconds later. The probe response time is defined herein as the time it takes the temperature sensor to respond through 63.2% of the total temperature change. This slow of a response time is unacceptable in many applications. The slow response time can be attributed to the fact that the resistive element is mounted within a protective housing that typically includes pockets of air and bonding agents between the element and the housing. The pockets of air can considerably reduce the thermal conductivity between the media and the resistive element resulting in a slower time constant of the probe.